KOTES OK THE ZYG^NMiESi. 167 



will add to our scientific knowledge, but only increase the doubt at 

 present existing. ( To be contmued. j 



[Note. — So far as Mr. Hewett's paper is a criticism of our own 

 writings on this subject, we have taken the liberty of explaining the 

 differences of opinion we seem to hold by means of a series of brief 

 footnotes. We are sure our readers will prefer this to another paper 

 on a subject which successive communications seem as yet to push no 

 more forward. — Ed.] . 



Are Tephrosia bistortata (crepuscularia) and T. crepuscularia 

 (biundularia) distinct species?*' 



By WILLIAM HEWETT. 



The burning question of the hour among some British lepi- 

 dopterists appears to be whether, in T. hifitnrtuta and T. crepuscularia, 

 we have two distinct species, or merely a species and a well-marked 

 variety ? Many competent authorities — Doubleday, Guenee (? Ed.), 

 Adkin, Tutt, Fenn, Jones (A. H.), Prout, Robertson, Sheldon, Riding, 

 Hamni, Mason (J.), etc. — incline, or have inclined, to the former 

 belief, others— Zeller, South, Meyrick, Barrett, Bignell, Smallwood, 

 etc. — to the latter. 



Staudinger, in his Catahuj, shows two species, but, from the " ? " 

 placed in front of T. crepuscularia [biu)i(lularia), it is evident that he 

 entertains some doubt. Kane states that he has " an open mind on 

 the question." 



It will be observed that (almost without exception) all those 

 gentlemen who, themselves, have observed and taken both T. bistortata 

 and T. crepuscularia are unanimous in considering the insects to be 

 two species. Most of those who believe them to be one species, either 

 have their information second-hand, or else appear to have personal 

 experience of one species only, viz., T. crepuscularia (biundularia). 



It may be Avell if I state at the outset what my ideas of a species 

 are. I consider the terse definitions of the term " species," as given 

 by the botanist, De Candolle, and by the zoologist, Swainson, and set 

 forth by Wallace {Darwinis)ii, p. 1), to be a satisfactory interpretation. 

 Wallace writes: — "The term 'species' was thus defined by the 

 celebrated botanist, De Candolle : ' A species is a collection of all the 

 individuals which resemble each other more than they resemble any- 

 thing else, which can, by fecundation, produce fertile individuals, and 

 which reproduce themselves by generation in such a manner that we 

 may, from analogy, suppose them all to have sprung from one single 

 individual.'" The zoologist, Swainson, gives a somewhat similar 

 definition: "A species, in the usual acceptation of the term, is an 

 animal which, in a state of nature, is distinguished by certain 

 peculiarities of form, size, and colour, or other circumstances, from 

 another animal. It propagates, ' after its kind,' individuals perfectly 

 resembling the parent. Its peculiarities, therefore, are permanent." 

 Absolutely there is no such thing as a species in science. It is only a 

 term for an arbitrary group. The information I have been able to 

 collect from various collectors covers 20 English, 13 Irish, 4 Scotch, 

 and 2 Welsh counties. 



* Abstract of a paper read before the South London Entomological Society 

 Jan. 14th, 1897. 



